History of Coatings

Date: Thu, 29 Jan 1998
From: Marc James Small msmall@roanoke.infi.net

Alexander Smakula combined the two elements necessary for successful lens coatings, fluoride compounds and vacuum. He began this while completing his doctorate in an internship at the small German optical works of Pohl; afterwards, he was hired by Zeiss, where he completed the process in 1935. Zeiss began the commercial production of coated lenses in 1937; I own a 1.5/5cm CZJ Sonnar in Contax RF mount dating from 1939 which is both coated and marked with the epic red "T", and I have a number of other Sonnars from 1940 and '41 in both Contax and Leica mount which are so marked and coated.

Kodak and, I believe, Wollensak, developed the same process independently, and at about the same time. Their error was their failure to see the marketing edge it would provide. Zeiss trumpeted their coatings, but the war cut off their sales.

After the War, Zeiss licensed the process selectively: clearly, Leitz did NOT have access to it until the Zeiss patent expired in '55, though Schneider and Voigtlander did. Thus, Zeiss lenses were HARD-coated from '37 onwards and, by 1942, all CZJ production photographic lenses are so coated. The soft coatings do exist, but these are on lenses from other houses not privy to the Zeiss patent, where they had to resort to the drip process which left a moist and soft coating.

Zeiss later pooled their expertise with Pentax to produce the first multi-coating, used initially by Zeiss around 1968 on industrial and scientific optics and by Pentax on camera lenses in early '71. Later 2.8F Rolleis are known to exist with multicoated lenses, though these lack the "T*" markings; there may be 3.5F's which were multi-coated, as well, though I am still awaiting the List Member who will report such.

Alexander Smakula emigrated to the US after the War and was the head of the Physics Department at Harvard during the late 1950's and early 1960's when this was one of the bases for the American nuclear-bomb programme.

msmall@roanoke.infi.net FAX: +540/343-7315

Mr Small is a noted expert on Zeiss and related optics.

Source: http://medfmt.8k.com/bronrecoatings.html